This invention relates to urethane foam compositions.
In one of its more specific aspects, this invention relates to low flame spread, spray-in-place foams suitable for insulation.
The use of low flame spread urethane-based foams as insulation is well known. Such materials are widely used on vertical surfaces, such as storage tanks, where application by spraying is practical. Such materials usually contain various halogen and phosphorous compounds in order to impart a flame spread (ASTME-84) of 25 or less. The inclusion of such halogen compounds in foams contributes significantly to their costs and considerable economic benefits could be realized if a suitable foam system could be developed which resulted in a reduction in the quantity of halogens, but which foams otherwise possessed satisfactory flame spread and insulation values. The use of halogens also results in reduced physical properties of the foams, such properties being compressive strength, tensile strength, dimensional stability and the like.
The present invention provides such foams. While, in general, the prior art foams of comparable flame spread contain about 6 weight percent bromine and about 4.5 weight percent chlorine, the foams of this invention contain about 2.5 weight percent bromine and about 2.5 weight percent chlorine. This invention further improves the commercial usefulness of polyurethane spray foams by providing a foamable composition incorporating a brominated diol. These foams have a 25, or less, flame spread, and exhibit excellent foam-substrate adhesion when applied to fuel oil storage tanks at temperatures between 100.degree. and 160.degree. F.